The present invention relates to bis(cis-3,3,5-trimethylcyclohexyl) phthalate comprising three stereoisomers in a specific proportion and a preparation process therefor, dl-bis(cis-3,3,5-trimethylcyclohexyl) phthalate, an optically active bis(cis-3,3,5-trimethylcyclohexyl) phthalate and a preparation process therefor, meso-bis(cis-3,3,5-trimethylcyclohexyl) phthalate, as well as to a thermoplastic resin composition and a heat-sensitive tacky adhesive each containing the bis(cis-3,3,5-trimethylcyclohexyl) phthalate as a solid plasticizer, a heat-sensitive tacky adhesive sheet using the heat-sensitive tacky adhesive and a production process therefor.
The bis(cis-3,3,5-trimethylcyclohexyl) phthalate comprising three stereoisomers in a specific proportion, dl-bis(cis-3,3,5-trimethylcyclohexyl) phthalate and meso-bis(cis-3,3,5-trimethylcyclohexyl) phthalate are useful as additives for delayed tack adhesives (heat-sensitive tacky adhesives), hot-melt adhesives, thermal transfer receiving materials, photosensitizers for color photography, hot-melt ink-jet inks, vibration absorbing materials, pencil lead, and vinyl chloride resin compositions, as well as plasticizers or stabilizers for lubricating oils and heating media. The optically active bis(cis-3,3,5-trimethylcyclohexyl) phthalate is useful, for example, as optically resolving agents and intermediate materials for pharmaceutical products and other fine chemicals.
Bis(3,3,5-trimethylcyclohexyl) phthalate can be used as a solid plasticizer in heat-sensitive tacky adhesives for use in xe2x80x9cdelayed tackxe2x80x9d labels. For example, Japanese Unexamined Patent Application Publication No. 2000-53874 discloses a thermoplastic resin composition comprising a thermoplastic resin and bis (3,3,5-trimethylcyclohexyl) phthalate including a trans-isomer and a cis-isomer in a weight ratio of the former to the latter of 0/100 to 40/60 and mentions that this composition can be used as a heat-sensitive tacky adhesive. The literature also mentions that a heat-sensitive tacky adhesive sheet comprising a heat-sensitive tacky adhesive including bis(cis-3,3,5-trimethylcyclohexyl) phthalate (melting point: 93xc2x0 C.) as a solid plasticizer has more excellent blocking resistance and adhesive strength than conventional heat-sensitive tacky adhesive sheets comprising dicyclohexyl phthalate as a solid plasticizer. However, demands have been made in some applications on solid plasticizers that can further improve blocking resistance and adhesive strength or solid plasticizers that have further highly durable adhesive strength and transparency.
E. G. Peppiatt and R. J. Wicker have reported the physicochemical properties of bis(3,3,5-trimethylcyclohexyl) phthalate and have mentioned that bis(cis-3,3,5-trimethylcyclohexyl) phthalate has a melting point of 93xc2x0 C. and bis (trans-3,3,5-trimethylcyclohexyl) phthalate has a melting point of 57xc2x0 C., in J. Chem. Soc., (1955) 3122. There is no report referring to the physicochemical properties, specifically the relationship between its three-dimensional structure and melting point and other properties, other than the above report.
Accordingly, an object of the present invention is to provide bis(cis-3,3,5-trimethylcyclohexyl) phthalate, a preparation process therefor and a thermoplastic resin composition that are useful for the preparation of a heat-sensitive tacky adhesive having excellent adhesive strength and blocking resistance.
Another object of the present invention is to provide bis (cis-3,3,5-trimethylcyclohexyl) phthalate, a preparation process therefor and a thermoplastic resin composition that are useful for the preparation of a heat-sensitive tacky adhesive having highly durable adhesive strength and transparency.
A further object of the present invention is to provide a novel stereoisomer of bis(cis-3,3,5-trimethylcyclohexyl) phthalate.
Yet another object of the present invention is to provide a novel optically active bis(cis-3,3,5-trimethylcyclohexyl) phthalate and a preparation process therefor.
Another object of the present invention is to provide a heat-sensitive tacky adhesive and a heat-sensitive tacky adhesive sheet that have excellent blocking resistance and/or adhesive strength and a preparation process for the heat-sensitive tacky adhesive sheet.
A further object of the present invention is to provide a heat-sensitive tacky adhesive and a heat-sensitive tacky adhesive sheet that can sustain high adhesive strength and transparency over a long period of time.
After intensive investigations to achieve the above objects, the present inventors have reveals that bis (cis-3,3,5-trimethylcyclohexyl) phthalate obtained by the reaction between cis-3,3,5-trimethylcyclohexanol and phthalic acid or a reactive derivative thereof includes three stereoisomers and have found that, when the compound comprising the three stereoisomers in a specific proportion is used as a solid plasticizer of a heat-sensitive tacky adhesive, the resulting heat-sensitive tacky adhesive has markedly improved properties such as blocking resistance, adhesive strength and transparency, and that the optical resolution of a mixture of the stereoisomers of bis(cis-3,3,5-trimethylcyclohexyl) phthalate can yield an optically active bis(cis-3,3,5-trimethylcyclohexyl) phthalate. The present invention has been accomplished based on these findings.
Specifically, the present invention provides, in an aspect, bis(cis-3,3,5-trimethylcyclohexyl) phthalate comprising stereoisomers represented by following Formulae (1), (2) and (3) and satisfying the following conditions: 
wherein a, b and c are mole percentages of the stereoisomers represented by Formulae (1), (2) and (3), respectively.
The present invention provides, in another aspect, a process for the preparation of bis(cis-3,3,5-trimethylcyclohexyl) phthalate, comprising the steps of allowing cis-3,3,5-trimethylcyclohexanol to react with phthalic acid or a reactive derivative thereof and purifying the resulting mixture of stereoisomers of bis(cis-3,3,5-trimethylcyclohexyl) phthalate to thereby yield bis(cis-3,3,5-trimethylcyclohexyl) phthalate comprising stereoisomers represented by Formulae (1), (2) and (3) and satisfying the following conditions:
a+b+c=100, and 50 less than a+b or 50 less than c
wherein a, b and c are mole percentages of the stereoisomers represented by Formulae (1), (2) and (3), respectively.
The mixture of stereoisomers of bis(cis-3,3,5-trimethylcyclohexyl) phthalate is purified, for example, by crystallization.
The present invention further provides dl-Bis(cis-3,3,5-trimethylcyclohexyl) phthalate comprising a compound represented by following Formula (1) and a compound represented by following Formula (2): 
The present invention provides, in yet another aspect, an optically active bis(cis-3,3,5-trimethylcyclohexyl) phthalate represented by following Formula (1) or (2): 
In another aspect, the present invention provides a process for the preparation of an optically active bis(cis-3,3,5-trimethylcyclohexyl) phthalate, comprising the steps of allowing cis-3,3,5-trimethylcyclohexanol to react with phthalic acid or a reactive derivative thereof and optically resolving the resulting mixture of stereoisomers of bis(cis-3,3,5-trimethylcyclohexyl) phthalate to thereby yield an optically active bis (cis-3,3,5-trimethylcyclohexyl) phthalate represented by Formula (1) or (2).
The present invention provides, in a further aspect, meso-bis(cis-3,3,5-trimethylcyclohexyl) phthalate represented by following Formula (3): 
The present invention provides, in yet another aspect, a thermoplastic resin composition comprising a thermoplastic resin and a solid plasticizer, which solid plasticizer comprises stereoisomers represented by Formulae (1), (2) and (3) and satisfying the following conditions:
a+b+c=100, and 50 less than a+b or 50 less than c
wherein a, b and c are mole percentages of the stereoisomers represented by Formulae (1), (2) and (3), respectively.
The thermoplastic resin composition may further include a tackifier or may be an aqueous composition including the thermoplastic resin dispersed in water.
In another aspect, the present invention provides a heat-sensitive tacky adhesive comprising the thermoplastic resin composition.
In a further aspect, the present invention provides a heat-sensitive tacky adhesive sheet comprising a base sheet and a tacky. adhesive layer formed at least on one side of the base sheet, which tacky adhesive layer comprises the heat-sensitive tacky adhesive.
In addition and advantageously, the present invention provides a process for producing a heat-sensitive tacky adhesive sheet, comprising the step of applying the heat-sensitive tacky adhesive at least on one side of a base sheet to thereby form a tacky adhesive layer.
In the above formulae, R and S are R,S-expression of configuration and are symbols of rectus and sinister, respectively.